Excess voltage protective device



June 4, 1946. s, H, JR 2,401,586

EXCESS VOLTAGE PROTECTIVE DEVICE Filed April 18, 1942 Inventor":

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Patented June 4, 1946 assist j v EXCESS VOLTAGE PROTECTIVE DEVICE SidneyR. Smith, Jr., Pittsfield, Mass, asslgnor to General Electric Company, acorporation of New York Appllcationdpril 18, 1942, Serial No. 439,507

My invention relates generally to excess volt age protective devices andparticularly to means for preventing foreign objects from interferin 2Claims. (Cl. 200-115) may be suitably supported from a, pole carrying Ith transmission line or the like, not shown, as

with the correct operation of such protective'devices.

Protective devices for protecting against high- H voltage surges, suchas the well-known expulsion protector tube or other forms of lightningor surge arresters are often used in connection with the protection oftransformers, a, circuit-interrupting device, such as a fuse cutout orthe like, being connectedin series with the line side of the transformerand the surg arrester being connected with one terminal of the fusecutout to provide a path to ground for voltage surges. Since the supportfor the surge 'arrester provides a space for foreign objects, such asbirds, to alight, service outages frequently result from arc-overs whichhave been initiated by the foreign objects establishing a low-resistancepath from one of the fuse terminals to ground. For example, birds whichalight on the supporting means for the surge arrester are attracted bythe adjacent bright metal terminal parts and initiate an arcover bypecking atthese parts.

. It would be desirable to provide means for guarding against thisdanger. Accordingly it is an object of my invention to provide a new andimproved surge arrester and support therefor which is substantiallybirdproof.

It is another object of my invention to provide an expulsion protectivetype surge arrester which may be readily removed by a service manwithout danger to life or property.

Further objects and advantages of my invention will become' apparent asthe following dcscrlption proceeds and the features of novelty whichcharacterize my invention will b pointed out with particularity in thclaims annexed to and forming a part of this specification.

For a better understanding of my invention,

by a supporting strap or hanger construction, generally indicated at i2,which is adapted to surround a central portion of reduced diameter is ofthe insulator It. The details of the hanger construction l2 formno partof the present invention but. are disclosed and claimed in myconcurrently fied copending application Serial No. 439.506 filed joint ywith Ralph S. Bennett, and assigned to the same assignee as the presentapplication. Insulator or supporting structure ll supports in spacedrelationship upper terminal assembly l4 and lower terminal assembly I!which are preferably of the type disclosed and claimed in theabove-mentioned copending application and these terminalassemblies l4and i5 are preferably connected to suitable line terminals.

Th e ectrical circuit between terminal assemblies I4 and I5 is completedthrough upper fuse link supportin arm It, a fuse link generallyindicated at H, lower fuse-link supporting arm I8,

and conducting member I! which pivotally supports lower fuse-linksupporting arm l8 and electrically interconnects it with lowerterminalassembly IS. A suitable spring 20 is provided for biasingpivotally mounted lower fuse-link supporting arm 18 in acounterclockwise direction as viewed from Fig. 2, thereby providingtension on fuse link IT to cause rapid separation of the fuselinkterminals upon rupture of th fusible element. Although I have disclosedupper and lower be understood that these supporting arms might referencemay be had to the accompanying drawing in which Fig. 1 is an elevationalview of a fuse cutout and associated birdproof surge protector embodyingmy invention, Fig. 2 is a view partly in section taken on lin !---I' ofFig. 1, Fig. -3 is n exploded view of a portion of the r e P tector andsupport therefor, and Figs; 4, 5, and 6 are modifications of blrdproofsurge protectors embodying my invention.

Referring now to Figs. 1 to 3 of the drawing, I have illustrated thebirdproof surge protector embodying my invention as associated with aspe-- ciflc type of fuse cutout. It should be understood, however, thatthe specific typeof fuse cutout illustrated is merely for the purpose ofillustration since my invention is applicable to any circuit-" beconstructed of inherently resilient material in which case it wouldbeunnecessary to provide additional'spring means. such as 20.

Fuse link I! preferably comprises a fusible element and, if necessary, aparallel strain wire, not

-sl'iown, enclosed within an insulating tube 2 I. The

ends of the fusible element which may be paralled by a strain wire areconnected to the ends of flexible cable portions 22. one of which isconnected to upper fuse-link terminal 23 and the other to lowerfuse-link terminal 24. These fuselink terminals are preferabl'y'providedwith a loop or other means for inserting a switch stickto permit readyre-fusing of the cutout in a manner which will be obvious from Figs. 1and 2. Upper and lower fuse-link supporting arms l6 and is are providedwith spring-biased clamping or jaw members 25 and 26. respectively; Thefuse link If may have the u per and lower ends thereof inserted in theseclamping members which are constructed to facilitate ready. insertionand removal of the fuse links I I. The fuse cutout described heretoforeforms no part of the present invention Since the hanger construction i2,as shown in ing application which is particularly adaptable v for usewith a hanger construction, such as 12. Conducting support or member 21,preferably extends at right angles from insulator I I with reference toupper and lower fuse-link supporting arms I3 and It. Any suitable surgearrester may be supported by member 21 and. accordingly, I haveillustrated a surge arrester oi the expulsion protector tube typedisclosed and claimed in United States Letters Patent 2,050,397. Such anexpulsion protector tube type of surge arrester comprises a pair ofspaced electrodes. one of which is connected to the line to be protectedand the other to a suitable ground. To insure early extinguishment oithe are drawn between the'electrodes due to a voltage surge, adielectric struc ture is provided surrounding the gap between theelectrodes, thereby confining the arc space to maintain a high arevoltage. This dielectric structure is furthermore composed of a materialcapable of evolving large quantities of substantially non-ionized gaswhen in close proximity to an arc discharge. Such an expulsion protectortube type surge arrester is shown in Fig. l in which the dielectricstructure comprises a tube 29 having a conducting terminal 29 at one endthereof and a conducting terminal 30 at the other end (see Fig. 3).These terminals 29 and so are preferably threadedly mounted on thedielectric structure comprising tube 28. In order rapidly to extinguishany are drawn between the electrodes, not shown. contained within thetube 29, the bore of the tube and, consequently, the electrode withinthis tube bore is very small. It terminal 29 were connected directly tothe high-voltage line to be protected, difliculties due to coronadischarge from this small electrode would occur and, to prevent this,conducting terminal 29 of the expulsion protector tube type 01 surgearrester is not connected directly to terminal I4 but instead has a gap3| interposed between terminal 29 and an electrode 32, which, in turn,is connected to terminal assembly l4. Electrode 32 preferably comprisesa bent rod, whereby the setting of gap 3| may be adjusted by merelysliding the rod in terminal assembly l4. With this arrangement, terminal29 and the electrode associated therewith contained within tube 23 arenormally maintained at a low potential relative to the potential of theelectrode 32. The terminal 33 of the expulsion protector tube type ofsurge arrester illustrated in Figs. 1

to 3 is electrically connected to conducting support 21, which, in turn,is connected to ground through hanger construction l2.

In order to permit ready removal and replacement of tube 23 and theassociated terminals 29 and 3., terminal 33 is preferably provided withtwo parallel contact faces 33 and diametrically opposed trunnions 34.Conducting support or member 21 on the other hand is provided withcooperating contact portions 35 for engaging with parallel contact faces33. Also, cooperating contact portions 33 include trunnion receiving 4notches 39 which open in a downwardly direction so that the trunnions 34may be inserted therein by an upward movement. The contact faces 33 orterminal 30 are preferably provided with indentations 31 into whichembossed portions 38 of coopcrating contact members 35 may be insertedto latch terminal 3|! into firm conducting engagement with cooperatingcontact portions 35 supported by conducting member 21. To insure goodcontact between these members, cooperating contact portions 35 arepreferably somewhat resil lent to grasp closely contact faces 33. Asuitable hook or switch stick receiving portion 39 may be associatedwith upper terminal 29 to' facilitate ready removal of the expulsionprotector tube surge arrester comprising tube 28 and terminals 29 and30. By merely pulling outwardly on hook 39, tube 28 will be rotated withtrunnions 34 as a pivot so as to force embossed portions 38 out ofindentations 31 whereupon tube 28 and associated terminals 29 and 30 arereleased and may be completely removed from conducting support 21. Toinsert the expulsion protector type surge arrester in position onconducting support 21, a lineman would simply move tube 28 and itsassociated terminals, supported on a switch stick by hook 39, in anupward direction until trunnions 34 engage notches 35 after which thetube would be rotated about trunnions 34 until latched by 1 means ofembossed portions 33 and indentations 31. It should be understood thatoperation of the expulsion protector tube type of surge arresterillustrated entails an upward force on support 21 due to the rapidexpulsion of arc gases iromtube 23. The removable mounting arrangementfor tube 28 limits the upward movement of the tube inasmuch as trunnions34 are restrained from moving upward by notches 29. with my new andimproved arrangement. the setting of gap 3| remains constant at a fixeddistance and it is, consequently, possible to remove asurge arrester,such as illustrated, from service and replace it with a new one 01' thesame standard dimensions, maintaining the setting of gap 3| withoutadditional adjustment being required. Furthermore, this replacement maybe accomplished while the associated transmission line is stillenergized.

With the arrangement described thus far, it will be obvious from Fig. 1that, without additional means, foreign objects. such as birds mightalight on conducting support 21 and peck at electrode 32, therebyinitiating an arcover with a resultant service outage. To prevent this,I provide in accordance with my invention a bird guard 21" which mightbe molded from a plastic material. such as aceto butyrate or the like,and which is so shaped that it could readily be snapped over the edgesof arm 21. With this arrangement foreign objects, such as birds, can nolonger alight on conducting support 21, thereby eliminating anydifliculty in this regard.

Although in Figs. 1 to 3, I have illustrated a surge arrester associatedwith a fuse cutout. such a surge arrester might be supported adjacentthe high-voltage terminal of a transformer, for example. and, in Fig. 4I have chosen to illustrate a modification of my invention applied tothe highvoltage bushing 40 of a transformer, not shown. A suitableconducting support 4| of relatively short length is welded or otherwiseiastened to the grounded transformer tank, only a small conductorportion 42 being shown in Fig. 4. A suitable expulsion protector tubetype of surge arrester comprising tube 43 and terminals 44 and 45,respectively, has the lower terminal 45 thereof electrically connectedto conducting support 4| as by means of hollow bolt 46 passing through aslotted opening 4'! in conducting support 4|. The opening in bolt 45,not shown, permits gases to escape from tube 43 during operationthereof. With this arrangement, the expulsion protector tube type ofsurge arrester is mounted in a substantially vertical position to form agap 48 between upper tube terminal 44 and an electrode 49, electricallyconnected to the transformer terminal associated with bushing 40.Adjustment of the gap 48 may be accomplished by moving tube 43horizontally on conducting support 4|, which may be accomplished byvirtue of the slot 41. Also because of the relatively short arm 4| andthe vertical position of the expulsion protector tube type surgearrester, the arrangement of Fig. 4 is substantially birdproof sincethere is insufiicient space for a bird to alight on arm 4|. Further toinsure such birdproofing, it may be desirable to use a bushing terminalguard 50 which may be substantially identical to that disclosed andclaimed in United States Letters Patent 2,263,319, granted November 18,1941, upon an application of E. D. Treanor, and assigned to the sameassignee as the present application. I have discovered that, by usingthe short conducting support 4| of Fig. 4, the surge arrester may bemounted on the transformer bushing and the entire unit including thetransformer shipped in a standard crate, which is not possible when alonger conducting support 4| is utilized.

To prevent insects from entering the lower open end of tube 43 thru theopening in hollow bolt 45 it may be desirable to provide an insect guardsuch as 5| comprising a flexible metal plate which is supported by bolt45 and bent over to close the opening at the bottom of the expulsionprotector tube. This will prevent insects from building their nestswithin the bore of the tube prior to the first tube operation, and sinceflexible insect guard 5| will be blown downwardly by the expelled gaseswhen the tube operates, it will also serve as an indicator with respectto whether or not the surge arrester has operated. Such a guard mightalso serve the additional purpose of a name plate for the device.

In Fig. 5, I have shown a modification of the arrangement disclosed inFig. 4 with the corresponding parts thereof designated by the samereference numerals. Instead of using the short supporting arm 4| asshown in Fig. 4, a longer supporting arm 4| is used, in which case, tube43 is mounted at an inclined position somewhat similar to that disclosedin Fig. 1 rather than the more nearly vertical position indicated inFig. 4. To permit adjustment of gap 48, electrode 49' comprises a bentrod similar to rod 32 of Fig. 1. To prevent birds from roosting oralighting on conductor support 4|, I provide a suitable insulating guard52 which substantially fills the space between bushing 40 and tube 43and which is suitably fastened as at 53 to conducting support 4|. 7

It might be desirable to provide such a surge arrester in connectionwith the conventional enclosed type of fuse cutout such as is disclosedin United States Letters Patent 2,081,813, granted May 25, 1937, upon anapplication of B. R. Hermann, and assigned to the same assignee as thepresent application. Accordingly,

supported from a crossarm or the likeby means of a hanger 55 cemented tothe rear wall of the cut-out housing. An expulsion protector tube.

type of surge arrester comprising tube 43 and terminals 44 and 45 may besupported from I hanger 55 by means of a strap 56 electrically connectedto lower terminal 45. A suitable gap 51 may be provided between terminal44 and an electrode 58, which may consist of a straight rod bent at oneend, the rod extending into the enclosed housing of the cutout throughopening 59 and being electrically connected to a line terminal withinthe housing. The setting of gap 51 can then be adjusted by merelytwisting the rod sulating jacket, it will be impossible for a, bird toinitiate an arcover by alighting thereon and engaging electrode 58.

While I have shown and described several embodiments of my invention, Idesire to have it understood that the specific forms shown are merelyillustrative and I intend in the appended claims to cover all suchchanges and modifications as fall within the true spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In combination, an insulating support, a supporting arm of conductingmaterial extending outwardly with respect to said insulating support,said supporting arm including contact portions having trunnion-receivingnotches therein, a surge arrester of the expulsion type including aterminal having trunions extending therefrom adapted to be received bysaid trunnion-receiving notches, latching means for latching said surgearrester in a predetermined position on said support so that saidterminal of said surge arrester is electrically engaged by the contactportions of said supporting arm, and

, a guard of insulating material mounted on said in Fig. 6, I havedisclosed such an enclosed type of cutout generally indicated at 54which may be supporting arm between said insulator and said surgearrester for preventing foreign objects such as birds from standing onsaid supporting arm and short circuiting said surge arrester.

2. The combination with an electric switching device having aninsulating support and a pair of spaced terminal contacts, means forsupporting an electric switching element from said support andelectrically connected between said contacts, a supporting arm ofconducting material extending outwardly with respect to said insulatingsupport, said supporting arm including contact portions havingdownwardly opening trunnion-receiving notches therein, a surge arresterof the expulsion type including a terminal having an opening thereinfrom which gases may be expelled. upon operation of said surge arresterand including trunnions extending therefrom adapted to be received bysaid trunnion-receiving notches, and means including embossed portionsfor latching said surge arrester in a predetermined position on saidsupport by rotating said surge arrester about said trunnions in saidtrunnion-receiving notches.

SIDNEY R. SMITH, JR.

